Multiphoton entangled quantum states are key to advancing quantum technologies such as multiparty quantum communications, quantum sensing, or quantum computation. Their scalable generation, however, remains an experimental challenge. Current methods for generating these states rely on stitching together photons from probabilistic sources, and state generation rates drop exponentially in the number of photons. Here, we implement a system based on active feed-forward and multiplexing that addresses this challenge. We demonstrate the scalable generation of four-photon and six-photon Greenberger-Horne-Zeilinger states, increasing generation rates by factors of 9 and 35, respectively. This is consistent with the exponential enhancement compared to the standard nonmultiplexed approach that is predicted by our theory. These results facilitate the realization of practical multiphoton protocols for photonic quantum technologies.

中文翻译：

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通过主动前馈和多路复用产生可扩展的多光子纠缠态

多光子纠缠量子态是推进多方量子通信、量子传感或量子计算等量子技术的关键。然而，它们的可扩展生成仍然是一个实验性挑战。当前生成这些状态的方法依赖于将来自概率源的光子拼接在一起，并且状态生成率在光子数量中呈指数下降。在这里，我们实现了一个基于主动前馈和多路复用的系统来解决这一挑战。我们展示了四光子和六光子 Greenberger-Horne-Zeilinger 状态的可扩展生成，将生成率分别提高了 9 倍和 35 倍。与我们的理论预测的标准非复用方法相比，这与指数增强一致。